Note: Descriptions are shown in the official language in which they were submitted.
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uNrvERsAL sAcKr~G FIANGE
Backaround and Summarv of the Invention
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The present invention relates to an improved system for mountin~ a
tool element subassembly to the output spindle of a power tool and more
particularly to a coupling flange that is adapted to accommodate and drivingly
engage both hubbed and non-hubbed types of abrasive disc subassemblies which
may be mounted to the spindle of a portable grinder.
The abrasive disc subassembly used on portable grinders genera]lv
consist.s of an abrasive disc that is carried by an internally threaded collar.
The collar is adapted to be mounted to the externally threaded spindle of the
~rinder. Typicallv, the direction of rotation of spindle when the motor in
the grinder is energized is such that the collar will self-thread onto the
spindle and bear against an annular shoulder formed on the spindle.
Alternatively, it has bee~ proposed to provide an annular composite "soft"
~asher assembly bet~een the collar on the abrasive disc subassembly and the
annular shoulder on the spindle to prevent the collar from becc~ing locked or
jammed against the annular shoulder of the subassembly. This latter t~e of
mounting construction is described in U.S. Patent No. 4,449,329, issued~May
22, 1984, for a "Composite Washer Ass~mbly", and assigned to the assignee of
the present invention. A further type of mounting construction employs a
supporting 1ange member that is positioned against the annular shoulder of
the spindle and at its radial distal end supports and rotationally drives the
abrasive disc.
In addition, a new mounting assembly for hubbed abrasive disc
subassemblies has recently been proposed that ccmprises an abrasive disc
having permanently attached to its backside a first metal backing flange or
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"hub". A second base flange member is positioned on the spindle of the
grinder against the annular shoulder of the spindle. The base flange member
has a pair of radially spaced annular drive surfaces on one side that are
adapte~ to engage corresponding radially spaced raised annular contact
surfaces on the backing flange or hub of the abrasive disc subassembly. The
other side of the base flange member is adapted to engage and be driven by the
annular shoulder on the spindle of the grinder or by a "soft" washer assembly
of the aforementioned type disposed between the base flange member and the
annular shoulder of the spindle.
Although this latter two-component system for driving grinding
wheels provides operational advantages over the previously employed systems,
it possesses the disadvantage of being incompatible with prior designed
non-hub-type abrasive disc subassemblies, which are most co~nonly available.
Specifically, a portable grinder equipped with the base flange member of the
aforementioned twn-component system will not drive a conventionally designed
abrasive disc subassembly not having the proper backing flange. Rather, in
order to use a conventional non-hub abrasive disc subassembly, the base flange
member must first be removed from the spindle of the grinder and replaced with
a conventional support flange member. This, of course, is undesirable not
only from a convenience standpoint, but also because the base flanae member,
once removed, is likely to be lost or misplaced, particularly in a ccmmPrcial
enviro~ment where portable qrinders are most frequently used.
Accordingly, it is the primary object of the present invention to
provide an improved drive system for mounting a tool element and, in
particular, an abrasive disc subassembly, to the output spindle of a power
tool such as a portable grinder.
In addition, it is an object of the present invention to provide an
improved mounting and drive assembly that is completely compatible with the
abrasive disc subassemblies for the newer two-conponen-t mounting system as
well as with the conventionally designed non-hub-type abrasive disc
subassemblies.
Brief Description of the Drawinqs
Additional objects and advantages of the present invention will
beccme apparent from a reading of the Det~iled Description of the Preferred
Embcdiments which make reference to the following set of drawinys in which:
Figure 1 is a perspective view of a typical pcwer tool to ~ich the
teachings of the present invention may be applied;
Figure 2 is an elevational sectional detail view of the right-angle
spindle of the tool shown in Figure 1, showing a first prior art mounting and
drive assembly;
Figure 3 is an elevational sectiona] detail view of the right-angle
spindle of the tool shown in Figure 1, showing a second prior art mounting and
drive assembly;
Figure 4 is an elevational sectional detail view of the right-angle
spindle of the tool shown in Figure 1, showing a mounting and drive assembly
according to the present invention when used with the abrasive disc
subassembly illustrated in Figure 2;
Figure 5 is an elevational sectional detail view of the right-angle
spindle of the to~l shown in Figure 1, showing a mounting and drive assembly
according to the present invention when used with the abrasive disc
s~ihassembly illustrated in Figure 3;
Figure 6 is an elevational sectional detail view of the right-angle
spindle of the tool shown in Figure 1, showing an alternative mounting and
drive assembly acoording to the present invention when used with the abrasive
disc subassembly illustrated in Figure 2; and
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Figure 7 is an elevational sectional detail view of the right-angle
spindle of the tool shown in Figure 1, sh~wing the alternative m~unting and
drive assembly according to the present invention when used with the abrasive
disc subassembly illustrated in Fi~ure 3.
Detailed Descri~tion of the Preferred Embodiments
With reference to Figure 1, there is illustrated a portable electric
grinder 10 with which the teachings of the present invention may be applied.
It will be appreciated by those skilled in the art, however, that the grinder
10 is only exemplary of a wide varietv of power tools and other devices to
which the invention may he applied. ~ith this in mind, the grinder 10
generally comprises a motor housing 11, a switch handle 12, a gear case 13, an
auxiliary handle 14, and a right angle spindle 15 for mounting a grinding
wheel subassembly or other tool element subassemblv. The guard for the
grinder has been removed in Fi~ure 1 for the sake of clarity. With further
reference to Figures 2 - 7, the spindle 15 is externally threaded and has an
annular shoulder 16 formed thereon. A tool element subassembly, or abrasive
disc subassembly 17, is threadably mounted on the spindle 15. m e abrasive
disc subassembly 17 includes a depressed center abrasive disc 18 carried by an
internally-threaded collar 19. It should be noted at this point that while
the preferred embodiments of the present invention are described and
illustrated herein in combination with depressed center abrasive disc
subassemblies, the present in~ention is equally applicable to flat "type 1"
abrasive disc subassemblies.
With particular reference to Figure 2, a first prior art mounting
construction is shown. The abrasive disc subassembly 17 in this construction
is supported by a flange member 20 that is positioned on the spindle 15 of the
grinder so that the central portion 21 of the flange abuts the annular
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sh.oulder 16 of the spindle 15. In addition, the flange member 20 is typically
configured so that the outer dist~1 end portion 22 supports the backside of
the abrasive disc 18 radlally outward of the depressed center portion of the
abrasive disc as shown. Thus, due to the direction of rotation of the spindle
15 relative to the threads on the spindle, when the motor in the grinder is
energized, the collar 19 of the abrasive disc subassembly 17 will self-thread
onto the spindle 15 so that the abrasive disc 18 bears against the distal end
portion 22 of support flange 20. Support flange 20 thus provides a drive
coupling between the spindle 15 of the grinder and the abrasive disc 18.
Referring to Figure 3, an additional prior art mountinq assemblv for
a "hubbed"-type grinding wheel is shown. In the construction illustrated in
Figure 3, the abrasive disc subassembly 24 comprises a depressed center
abrasive disc 18 that is permanently affixed to an internally threaded collar
19 adapted to be threaded onto the end of the spindle 15. In addition, the
abrasive disc subassemblv 24 includes a flexible metal bac~.ing flange 26 that
is also permanently attached to the backside of the abrasive disc 18 and thus
conprises part of the subassembly 24 that is disposed of when the abrasive
disc 18 is worn out. The backing flange 26 includes a pair of raised or
elevated, radially spaced annular contact surfaces 27 and an annular drive
surface 30 at its outer distal end that drivingly engages and supports the
backside of the ahrasive disc 18 radially cutward of the depressed center
portion of the abrasive disc 18. A second base flange member 28 is provided
that is adapted to be positioned against the shoulder 16 of the spindle 15 and
is configured to drivingly engage the backing flange 26. In particular, the
base flange member 28 includes a pair of radially spaced annular drive
surfaces 29 that are adapted to drivingly engage the correspondingly radially
~spaced annular contact surfaces 27 on the backing flange 26 of the abrasive
disc subassembly 24. In this manner, the rotational force frcm the spindle 15
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is transferred to the abrasive disc subassembly 24 via the frictional
interface between the driving surfaces 29 on the base flange member 28 and the
raised contact surfaces 27 on the backing flange member 26. This rotational
~orce is in turn applied directly to the abrasive disc 18 via the frictional
interface between the abrasive disc 18 and the distal end drive surface 30 of
the backing flange 26.
Significantly, it will be appreciated that the tt~-ccmponent
mounting system illustrated in Figure 3 provides a self-tightening feature as
the grinder is operated. In particular, in the unloaded condition, due to the
relatively small point contacts between the drive surfaces 29 on the base
1ange member 28 and the contact surfaces 27 on the backing flange 26, the
degree of fiiction between the tw~ flange members is relatively low.
Therefore, when the abrasive disc 18 is initlally loaded and the subassembly
24 begins to slip relative to spindle 15, the abrasive disc subassembly 24
will immediately thread more tightly onto the spindle ]5. This in turn will
cause the backing flange 26 to flex and bear more tightly against the drive
surfaces 29 of the base flange member 28, therehy increasing the coefficient
of friction between the two flanqe members 26 and 28 and preventing further
slippage between the abrasive disc 18 and the spindle 15 frcm occurring.
q~he prior art two-component mounting system illustrated in Figure 3,
however, suffers the disadvantage of being incompatible with the non-hubbed
abrasive disc assemblies 17 of the type illustrated in Figure 2. This
disadvantage is particularly evident in ccmmercial environments where grinders
are most commonly used and abrasive disc subassemblies are frequently worn out
and xeplaced. It is not uncommon for the supply of replacement grinding wheel
subassemblies at a given job site to comprise a collection of both hubbed and
non-hubbed types. Thus, it is inconvenient and time consuming for an operator
on the job site faced with having to replace a worn hubbed wheel subassembly
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to disassemble and replace the drive assembly in order to install an unhubbed
t~heel subassembly. Accordingly, it can be appreciated that it is desirable to
provide a mounting and drive assembly that is compatible with both types o~
abrasive disc subassemblies.
The present invention solves this problem by providing a universal
couplinq flange member that is compatible with both the non-hubbed abrasive
disc subassembly 17 of the type illustrated in Fiqure 2, as well as the
hubbed~type of abrasive disc subassembly 24 illustrated in Figure 3.
Specifically, and with palticular reference to Figure 4, the coupling flange
35 according to the present invention is preferably formed frcm stamped metal
and is adapted to be positioned on the spindle 15 so that the central contact
surface 44 of the flange abuts the annular shoulder 16 of the spindle 15. The
flange 35 is configured to provide three separate drive surfaces 36, 37, and
38. When used in combination with a non-hubbed abrasive disc subassembly 17
of the type illustrated in Figure 2, the drive surface 38 at the distal end of
the flange 35 is adapted to drivingly engaqe and support the backsifle of the
abrasive disc 18 in the same manner as the flange 20 in the prior art
construction. Significantly, it will be noted that the distance "hl" in the
aYial direction between the drive surface 38 and the driving surfaces 36 and
37 is such that in the embodiment illustrated in Figure 4, the drive surfaces
36 and 37 of flange member 35 do not contact the backside,
or depressed center portion, of the abrasive disc
18, Accordingly, the driving force of the spindle 15 is transferred by the
coupling flange mRmber 35 to the abrasive disc subassembly 17 solely via the
frictional engagement between the radially outer distal end drive surface 38
of the coupling flange 35 and the abrasive disc 18.
Referring now to Figure 5, the use of the coupling flange member 35
according to the present invention in combination with the hubbed-type
abrasive disc subassembly 24 illustrat~d in Figure 3 is shcwn. The coupling
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~lange memker 35 is installed onto the spindle 15 so that the central contact
surface 44 of the flange abuts the annular shoulder 16 of the spindle 15 in
the sam~ manner AS that shown in Figure 4. However, the coupling flange 35 is
so configured that in this application the drive surfaces 36 and 37 radially
align with and hence drivingly engage the corresponding radially spaced raised
contact surfaces 27 on the backing flange 26 of the abrasive disc subassembly
24. The distal end drive surface 38 of the coupling flange member 35 remains
spaced from and out of engagem.ent with the abrasive disc subassembly 24 in
this application. This is due to the fact that the aforesaid distance "hl" in
the axial direction between drive surfaces 36, 37, and 38 of flange member 35
is less than the distance "h2" in the axial direction between contact surface
27 and distal end drive surface 30 of backing glange 26
radially beyond the depressed center portion of the
abrasive disc 18. Thus, the rotational
force of the spindle 15 is transferred to the coupling flange 35 by virtue of
the frictional interface between the coupling flange 35 and the annular
shoulder 16 of the spindle lS, and then applied to the abrasive disc
subassembly 24 via the frictional interface between the drive surfaces 36 and
37 on the coupling flange 35 and the contact surfaces 27 on the backing flange
26. It will be noted, h~wever, that due to the similar radial locations of
the drive surfaces 36 and 37 on the present coupling flange member 35 and the
corresponding drive surfaces 29 on the base flange member 28 illustrated in
Figure 3, the previouslv described self-tightening feature of the
twc-component mounting system illustrated in Figure 3 is retained by the
present invention.
At this point, it is further significant to note that the distal end
portion of the flange member 35 according to the present invention projects
dot~nt~ard at a much steeper angle relative to the horizontal than d oes the
distal end portion 22 of the prior art flange member 20 illustrated in Figure
2. ~,oecifically, t~hereas the distal end portion 22 of the flange member 20
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shown in Figure 2 projects downward at an angle of approximately 35 , the
distal end portion of the present flange member 35 projects downward at an
angle of approximately 75 (Figure 4). Thls .insures that the distal end
portion of the present flange member 35 will clear the backing flange 26 when
used with a hubbed wheel subassembly 24 (Figure 5) without projecting radially
out~ard a greater distance than that of a conventional flange member 20
(Figure 2). In other words, the overall diameter of the flange member 35 of
the present invention is essential~v equivalent to that of the prior art
flange member 20. ~ince grinding wheels are worn away fr~m their outer radial
periphery inward as they are used, it can be appreciated that it is desirable
that the drive system not unnecessarily comprise the usable amount of area on
the grinding wheel. Accordingly, it can be seen that the usable amount of the
grinding wheel is not reduced by the present invention.
Referring now to Figures 6 and 7, a further application of the
coupling flange member 35 according to the present invention in combination
with a "soft" washer assembly, for both the hubbed and unhubbed tvpe wheel
subassemblies are shown. In this application, an annular ccmposite washer
assembly 40 of the type illustrated and described in the aforementioned U.S.
Patent No. 4,449,329, entitled "Composite Washer Assembly", is installed on
the spindle 15 against the annular shoulder 16 of the spindle 15. m e
coupling flange m~mber 35 according to the present invention is then installed
onto the spindle 15 against the bottom surface of the ccmposite washer
assembly 40. The present coupling flange member 35 ls configured to provide a
se.cond annular contact surface 42 radially spaced from, and on the same axial
plane as, the central contact surface 44, so that both contact surfaces 42 and
~4 frictionally engage the washer asse~bly 40. miS construction serves to
improve -the torque transfer characteristics between the spindle 15, washer
assembly 40, and coupling flange 35.
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While the above specification describes the preferred embodiments,
it is understood that the present invention is subject to modifica~ion and
change without departing from the proper scope or fair meaning of the
accompanying claims.
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